The present invention relates to a reactive probe chip capable of recognizing a plurality of functional molecules, to be used for gene diagnosis, physiological function diagnosis and the like, and to a method for its fabrication.
Also, the present invention relates to a composite substrate wherein on at least a section of the surface thereof, a plurality of porous regions are arrayed as compartments encompassed by non-porous regions, or a plurality of non-porous regions are arrayed as compartments encompassed by porous regions, and to a method for its fabrication.
Detection of polymorphisms due to gene mutations, and particularly single base (codon) mutations, is not only effective for diagnosis of cancer and other diseases resulting from mutations, but is also necessary for indication of drug responsiveness and side-effects, and can be helpful for the analysis of the causative genes of multiple factor diseases, and for predictive medicine. The use of “DNA chips” for detection is known to be effective. The hitherto utilized “Gene Chip” by Affymetrix, which is a DNA chip containing immobilized short DNA chains, usually comprises over 10,000 oligo DNA fragments (DNA probes) mounted on an approximately 1 cm square silicon or glass plate using a photolithographic technique.
When a fluorescently-labeled DNA sample to be examined is allowed to flow over the DNA chip, the DNA fragments having sequences complementary to the probes of the DNA chip bind to the probes to perform detection of only those sections by their fluorescence, and thereby detecting and quantifying the specific sequences of DNA fragments in the DNA sample. It has already been demonstrated that this method can detect cancer gene mutations and gene polymorphisms.
Microarrays with cDNA immobilized on slide glass may also be used.
On the other hand, porous solids have been widely used in the prior art as carriers for catalysts, enzymes, microorganisms and the like, and are utilized as sites for various reactions. They are also used as functional materials for adsorption and separation, or as materials providing low heat or electrical conductivity. Porous glass or porous ceramics are used as porous solids, and methods of controlling the pore sizes or imparting functional groups have provided properties suitable for specific uses.
There were three principal problems in the prior art. DNA chips employing photolithography require at minimum four photomasks for each step of synthesis, and the photolithography, coupling and washing must be repeated four times. Since this is repeated the required times depending on the chain length, the cost is high (problem 1). Also, it is necessary to change each photomask in order to change the pattern, for which reason, DNA chips with various designs could not be flexibilly fabricated (problem 2).
That is, although the types of DNA probes to be immobilized on the DNA chip are previously decided and although it is easy to fabricate and supply such DNA chips at locations where the necessary equipment is available, different photomasks must be prepared for synthesis of each base in the probe. Therefore, the reaction process has may steps and it is difficult to fabricate in a flexible manner, DNA chips containing DNA probes for different purposes. High costs are also incurred. When the number of DNA probes required is small, the degree of integration of the DNA probes on the chip need not be so high. Rather, it is sometimes desirable for the chip to have the desired DNA probes immobilized in a more convenient manner. The DNA chip must also be provided at low cost and with high stability if it is clinically used to detect DNA polymorphisms of individuals.
Alternatively DNA Microarray chips prepared by spotting a solution of synthesized oligonucleotide at high density, is proposed. In this process, modifying groups are introduced after synthesis of the oligonucleotides and then the modified oligonucleotides are cut out and released from the carrier and purified. Further the purified oligonucleotides are reacted with the functional groups previously introduced onto the substrate glass. Thus, the process is very complex and the cost is therefore high (problem 3) as of the DNA chips produced by photolithography.
Which respect to substrates for probe chips, porous solids have a wide variety of applications, for example, carrier of probe chips such as DNA chips, and the like, but the use of porous solids having continuous porous regions throughout the entire surface has been limited in that only one function can be loaded on such a single and uniform substrate.
However, in recent advancements in scientific techniques, downsized devices is in ever greater demand and it has been desired to develop a composite substrate having unique utilities not found in the prior art, and a substrate having different reaction sites with a plurality of functions on the single substrate whereby the local areas of the substrate can be thermally or electrically insulated each other.
In light of the problems in the prior art, it is an object of the present invention to provide a composite substrate as a single substrate allowing a plurality of different functions to be loaded, as well as a method for its fabrication.